Forming Analysis of Natural Fibre Composites

Abstract

Weight reduction can significantly contribute to reducing Green House Gas (GHG) emissions from vehicles. In addition to the significant increase in the demand on transportation due to the increase in global population, there is an urgent need to reduce the weight of vehicles to increase their fuel efficiency and therefore to reduce global GHG emissions. Driven by ecological and economic interests, there has been an increasing use of plant based material systems in various applications over the past decade. Currently, one of the main challenges in using these material systems for use in automotive components is to understand the forming behaviour of this class of material systems. This work is designed to answer two key questions regarding the forming of natural fibre composites. The first one is when does failure initiate in this class of material systems, and what is the most effective measure for predicting it? To answer this question, hourglass samples with varying sample widths are stretched and then formed through the stamping press machine. The ARAMIS. system beneath the press machine provides displacement and strain deformation which could be used to determine the failure behaviour of the composites. This study proposes a new FLC for woven composites, which is more effectively in predicting the failure behaviour of the natural fibre composite than the conventional method as it can successfully eliminate the path dependency effect. This innovative failure criterion has been proven to be more effective than the existing failure criterion through FEA simulations. The second question that the current work tries to answer is how to improve the formability of natural fibre composites. The approach here is to perform dome forming tests in different treatment conditions, namely preheating, water treatment, and tailored blanks. It is found that, among all treatment, the water treatment works the best, and is more effective than the conventional treatment of preheating. Woven composite with a tailored shape becomes much more formable due to its woven nature of fibre reinforcement, while such improvement is insignificant in nonwoven composites. This study lays a foundation for rapid forming of this class of material system, and will in turn lead to possible weight savings in future vehicles.